Recently, considering environmental issues, attention has been paid to a vehicle employing a motor as a drive power source, such as an electric vehicle, a hybrid vehicle and a fuel cell vehicle. Such a vehicle includes a power storage unit implemented, for example, by a secondary battery or an electric double layer capacitor for supplying electric power to the motor, and converting kinetic energy to electric energy during regenerative braking and storing such electric power.
In such a vehicle employing the motor as the drive force source, in order to enhance acceleration performance and running performance such as travel distance, greater charge/discharge capacity of the power storage unit is desired. Here, a configuration where a plurality of power storage units are mounted has been proposed as a method of increasing the charge/discharge capacity of the power storage unit.
On the other hand, as the power storage unit stores electric energy utilizing electrochemical action, charge/discharge characteristics thereof are susceptible to a temperature. A general power storage unit is lower in the charge/discharge performance as the temperature is lower. Accordingly, in order to maintain prescribed charge/discharge performance, temperature management, in particular temperature increase control, of the power storage unit is important.
For example, Japanese Patent Laying-Open No. 11-26032 discloses a heating-up device for a battery in an electric vehicle, that raises a temperature of the battery mounted on the electric vehicle. According to this device, if a detected temperature of the battery is equal to or lower than a prescribed value when an instruction is issued from at least one of unlock detection means for detecting unlock of the vehicle, timer means for notification of a set time, and input means for input of operational information, control means carries out control such that an output current of the battery greater than a current required in the battery flows.
Though the heating-up device disclosed in Japanese Patent Laying-Open No. 11-26032 carries out control such that the output current of the battery greater than the required current flows when an instruction is issued from at least one of the unlock detection means, the timer means, and the input means described above, this publication does not provide sufficient disclosure of detailed control of the output current.
In other words, though it is effective to increase the output current of the battery from a viewpoint of increase in an amount of heat generation within the battery for promoting rapid temperature increase in the battery, on the other hand, it may lead to such disadvantages that electric power taken out of the battery or electric power loss caused in a converter or the like increases and energy efficiency of the entire power supply system is lowered. Therefore, in order to enhance running performance of the vehicle, rapid temperature increase of the battery while ensuring improvement in energy efficiency is required.
Japanese Patent Laying-Open No. 11-26032 described above, however, merely discloses a configuration for carrying out control for uniformly increasing the output current of the battery in any of a case that the vehicle is unlocked, a case that a set time has come, and a case that an operation through a remote controller from inside of a vehicle is input, and this publication is silent about means for solving these problems.
Therefore, the present invention was made to solve such problems, and an object of the present invention is to provide a power supply system capable of rapidly raising a temperature of a power storage unit while ensuring improvement in energy efficiency.
In addition, another object of the present invention is to provide a vehicle including a power supply system capable of rapidly raising a temperature of a power storage unit while ensuring improvement in energy efficiency.